Derek Williams

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Business travels and extra duties lately have brought some unexpected surprises. I find such “out of the box” adventures refreshing: pulling the rug out from under typical routines forces me to challenge assumptions and improvise. Here are some examples from the past two days.

The Right Sequence

During group architecture sessions, I needed to quickly create, modify and display sequence diagrams to demonstrate interactions among several new web services. Lacking my usual tools (and convinced there had to be a better mousetrap), I searched around and found websequencediagrams.com. This STTCPW site was exactly what I needed. Using it was faster than tools such as Visio Pro, and even faster than drawing and editing on whiteboards.

Weekend Jobs

Today I got word that some Quartz jobs weren’t running as expected during pre-production testing, where typical weekday processes were run as a logical business day on Saturday. The cron-expressions were correct, so I needed to see more. A look at the full jobs.xml revealed the culprit: this environment had been configured to use WeeklyCalendar rather than the usual AnnualCalendar. A quick temporary switch had Quartz working weekends with the rest of us.

Fog of WAR

Despite version labels and other indicators, a web app was behaving as if it was down-level in a key area. Since the WAR file hadn’t been obfuscated, I grabbed a copy of the JD-GUI decompiler for a closer look. Sure enough, the class in question was at an older level. When sources aren’t available or are in question, the JD Project tools are indispensable for moving past assumptions and getting to facts.

Decimal, with an E

New calls to my web services from VoiceObjects were sending certain decimal data in E notation. The underlying call flow objects were TTA – Literals/Digits with a digits?minlength=1;maxlength=14 grammar, so it should have been decimal from end to end. But there turned out to be an unexpected feature of the platform to convert to float whenever any arithmetic is done, with no access to DecimalFormat or other mechanisms to convert back. Since there was fortunately no loss of precision and since a problem correctly stated often solves itself, I knew exactly what to do: modify the web service to accept the format. Voxeo provides a great VoiceXML platform, but it has plenty of surprising nuances like this.

During today’s action, I needed to verify new custom HTTP header fields (#HeaderName# properties) in my SOAP web service calls originating from a Voxeo VoiceObjects (VO) call flow. This meant pointing VO to my favorite trace tool (Fiddler2) running as a proxy on localhost / 8888. This usually requires setting JVM parameters (proxyHost and proxyPort) on the embedded app server, overriding post URL ports, or using proxycfg, but I suspected VO had an easier way. Sure enough, after some poking around, I found it:

I recently built a voice response system with Voxeo‘s software: their VoIP IVR (Prophecy) and VoiceXML server (VoiceObjects). This stack is available in both on-premise (local install) and cloud versions (Evolution/VoiceObjects on Demand), and includes an Eclipse-based development environment, VoiceObjects Desktop for Eclipse (DfE). VoiceObjects (VO) takes a little getting used to, but is a nice platform for developing call flows. It sure beats hand-coding VoiceXML, and it integrated well with my Java service back-end.

VoiceObjects’ documentation is excellent, but I learned quite a lot by trial and error. So I thought I’d share a few tips and lessons learned.

Use scripts and expressions

VO’s library of objects is quite rich, but you will inevitably run into some requirement that needs more than just objects with properties. For example, I used nested concatenate expressions to build complex types for web service calls; split, index, findcell, strequal, and matchesregexp expressions to process web service results; and JavaScript to handle custom DTMF mappings. The prepackaged expressions are also helpful, such as the ones that grab ANI and DNIS from session state.

Set event handlers

It’ll take about 5 seconds to grow weary of the thickly-accented “service you are trying to reach is not available…” default message. Get a friendlier message with more root cause details by setting the event handlers in your top-level module (they’ll be inherited by child objects). Just open the Outline view, expand Event Handling section, and add away. You can add whatever outputs you’d like, and use different handlers for repeat occurrences.

Set default routing

Be sure you have a default routing (*) entry in the Prophecy Commander applications list, since surely someone will use the wrong SIP address or configure the wrong URI. With a default routing entry, callers at least land in a recognizable place.

Get Blink

VO’s built-in SIP Phone is very basic, so you’ll find yourself looking for alternatives. There are a lot of free SIP phones out there, but most require signing up to a service or can otherwise violate corp-rat security concerns. I settled on Blink. It’s a little buggy, but does the job.

Get an ATA

SIP phones are handy, but you’ll eventually want to pick up a POTS phone or cell and call into your IVR. While you can can assign PSTN phone numbers in Evolution/VoD, that doesn’t help with your local Prophecy install. That’s where Analog Telephone Adapter (ATA) gateways come in. I used the AudioCodes MP-114; the model with two FXO and two FXS ports provides both analog in and analog out options.

Get the latest version

Since Voxeo’s hosted environment uses VO 10, I started out with that version. But I quickly ran into some problems that required recent fixes. Voxeo was kind enough to build a custom VO 11 environment in an AWS instance for my cloud testing, but their GA hosted platform will be upgraded soon. In the mean time, there’s really no reason not to use one of the recent versions: 11 or 12.

Add debug outputs

VO provides a Log object for tracing purposes, but I often found it easier to use additional Output objects to hear trace messages on the call. By convention, I labelled these with a “Debug – ” prefix, and disabled them (but left them in place) when not used.

Use the logs

Even minor typos can cause VO to throw internal exceptions that leave you scratching your head. Sometimes you can diagnose these with Debug and Trace, but in most cases the VoiceObjects logs (viewable from DfE) provide the best information. If the problem is on the IVR side, use Prophecy’s built-in Log Viewer to hunt down the root cause.

Use the support forums

For some vendors, support fora are where problems go to die from neglect. But that’s far from the case with Voxeo. They have an excellent support team that quickly responds to issues. You can browse existing posts for common problems and easily add new tickets.